https://www.servocity.com/10t-0-125-1-8-bore-32p-shaft-mount-pinion-gear-steel/ This Pinion Gear's 1/8 inch Bore fits the goBILDA 5000 series bare motor output. The gear is 32 Pitch (32 teeth per inch), but 32 teeth divided by 25.4 mm / inch and - you may have guessed it - you get almost exactly a 0.8 MOD compatible tooth profile.